Deposition of metal-rich mine tailings, metal smelting, leather tanning, electroplating, emissions from gas exhausts, energy and fuel production, downwash from powerlines, intensive agriculture and sludge dumping are the most important human activities which contaminate aqueous systems with large mounts of toxic metals. The list of sites contaminated with toxic metals grows larger every year, presenting a serious health problem and a formidable danger to the environment. Although water treatment procedures have been developed to remove metals from aqueous environments, water treatment plants, for example, do a relatively poor job of removing toxic metals from residential and industrial aqueous waste, contributing to the overall problem.